Air-conditioning controlling method and device

ABSTRACT

A dew-point temperature sensor is provided in a data center. In an air-conditioning controlling device, a lower limit value for a supply air temperature wherein there is no danger of the occurrence of condensation within a data center is calculated from a dew-point temperature (an inside dew-point temperature) that is measured by the dew-point temperature sensor, and a setting value for the supply air temperature and a setting value for the supply air flow rate into the data center the from the air-conditioning device are determined based on the calculated lower limit value for the supply air temperature. Note that a dew-point temperature for the exhaust air from within the data center, a dew-point temperature for the supply air into the data center from the outside conditioning equipment, or a dew-point temperature of the outside air may be used instead of the inside dew-point temperature.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C, §119 to Japanese Patent Application No. 2010-021932, filed Feb. 3, 2010, which is incorporated herein by reference,

FIELD OF TECHNOLOGY

The present invention relates to an air-conditioning controlling method and device for controlling the supply air temperature and supply air flow rate from an air-conditioning device into a room that is subject to control, wherein the room that is subject to control is a room wherein is installed equipment wherein there is a danger of the occurrence of physical damage due to condensation.

BACKGROUND

Conventionally, in data centers wherein electronic equipment such as servers is installed, the exhaust heat from the equipment within the data center is treated through the supply of air from an air-conditioning device. (See, for example, Japanese Unexamined Patent Application Publication 2003-35441 (“JP '441”) and Japanese Unexamined Patent Application Publication 2009-140421.)

FIG. 10 illustrates a summary thereof. In the figure: 1 is a data center (a room that is subject to control); 2 is an air-conditioning device (a cooling device) that is provided within the data center; 3 is a rack that houses electronic equipment, such as servers, provided within the data center; 4 is an air-conditioning controlling device that is provided for the air-conditioning device 2; 5 is an outside conditioning equipment for adjusting the temperature and humidity of outside air and supplying the outside air into the data center 1; 6 is an exhaust fan for exhausting the exhaust heat from within the data center 1; 7 is a supply air temperature sensor for detecting the temperature of the air supplied into the data center 1 from the air-conditioning device 2; and 8 is a cooling medium circulating rate adjusting device for a test in the circulating rate of a cooling medium to the air-conditioning device

Note that there can be a variety of operations such as the compressor (COMP), the expansion valve, the hot gas bypass valve, and the like, as the cooling medium circulating rate adjusting device 8, but in this example, an example is illustrated that uses the compressor (COMP) as the cooling medium circulating rate adjusting device 8, as one example thereof. In the below, the cooling medium circulating rate adjusting device 8 shall be termed the COMP 8,

In this system, the air-conditioning device 2 is provided with a. cooling coil 2-1 and a fan 2-2, where a fan 3-1 is built into the rack 3. The COMP 8 is provided in a circulating flow path of the cooling medium to the cooling coil 2-1. Furthermore, in the air-conditioning device 2, the flow rate of the fan 2-2 (the supply air rate) is constant at 100%. The air-conditioning controlling device 4 inputs a measured value tspv for the temperature of the air that is supplied into the data center 1 from the supply air temperature sensor 7 and adjusts the inverter power (COMP INV) to the COMP 8 so that this measured value tspv of the supply air temperature matches a setting value tssp for the supply air temperature that has been set in advance. That is, the rate of supply of the cooling medium to the cooling coil 2-1 is controlled through adjusting the percentage value of the inverter power to the COMP 8 so that the measured value tspv of the supply air temperature will match the setting value tssp for the supply air temperature.

In this way, in the data center 1, the supply air flow rate from the air-conditioning device 2 is constant at 100% and the supply air temperature is caused to be constant, and the exhaust heat from the electronic equipment, such as servers, housed in the rack 3 is treated through the supply air from the air-conditioning device 2. In the data center 1, if the temperature of the supply air from the air-conditioning device 2 were too low, then condensation would occur, with the danger of causing physical damage to the electronic equipment within the data center 1. Because of this, in this system, while the outside air is dehumidified by an outside conditioning equipment 5 and drawn into the data center 1, a setting value tssp for a supply air temperature having a margin wherein condensation will not occur within the data center 1 is set in advance, where this setting value tssp for the supply air temperature is a constant value, and control is performed so that the temperature of the air supplied from the air-conditioning device 2 is constant. Note that as a technology that is similar to controlling to a constant supply air temperature, in JP '41 a cooling panel is provided at a sidewall of a rack, and the temperature of a thermal medium that is supplied to the cooling panel is controlled so that there will be no condensation on the surface of the panel.

However, in the system illustrated in FIG. 10, because the setting value tssp for the supply air temperature is set somewhat high so as to have a margin and this setting value tssp for the temperature of the supply air, which is set somewhat high, is a constant and control is performed so that the temperature of the supply air is constant, and because the flow rate of the supply air from the air-conditioning device 2 is 100% constant, there is a problem in that the loss of energy consumed is large.

The present invention was created in order to solve this type of problem, and the object thereof is to provide an air-conditioning controlling method and device able to reduce the temperature of the supply air, and, to that extent, reduce the flow rate of the supply air, to achieve energy conservation.

SUMMARY OF THE INVENTION

In order to achieve the object set forth above, the air-conditioning controlling method according to the present invention comprises: a step for measuring the dew-point temperature in the room that is subject to control; a step for calculating a lower limit value for the temperature of the supply air wherein there is no danger of the occurrence of condensation in the room that is subject to control; a step for determining a setting value for the supply air temperature based on the calculated lower limit value for the temperature of the supply air; and a step for determining a setting value for the flow rate for the supply air based on the calculated lower limit value of the temperature for the supply air.

In the present invention, the dew-point temperature of the room to be controlled is measured, and a lower limit value (tsmin1) of the temperature of the supply air wherein there is no danger of the occurrence of condensation within the room that is subject to control is calculated based on the measured value (trpv) of the dew-point temperature. For example, with the amount of margin defined as α, the lower limit value tsmin1 for the temperature of the supply air is calculated as tsmin1=trpv+α.

Additionally, a setting value tssp for the temperature of the supply air is established based on the calculated lower limit value tsmin1 for the temperature of the supply air, For example, with the lower limit value for the temperature of the supply air, constrained by the capability of the air-conditioning device, as the equipment-constrained supply air temperature lower limit value tsmin2, this equipment-constrained supply air temperature lower limit value tsmin2 is compared to the calculated lower limit value tsmin1 for the temperature of the supply air, and the higher of the lower limit values for the temperature of the supply air is defined as the setting value tssp for the temperature of the supply air.

Additionally, a setting value Qssp for the flow rate for the supply air is determined based on the calculated lower limit value tsmin1 for the temperature of the supply air. For example, a setting value tssp for the temperature for the supply air is determined based on the calculated lower limit value tsmin1 for the temperature of the supply air, and the setting value Qssp for the flow rate of the supply air is set based on the setting value tssp for the temperature of the supply air, which has been determined, with Qssp (CMH)=rated capability (kW)×3600/{ (assumed inflow temperature−tssp)×specific mass (kg,/m³)}.

In the present invention, a step may be provided for measuring the dew-point temperature of the exhaust air from the room that is subject to control and the dew-point temperature of the supply air from the outside conditioning equipment, instead of the step for measuring the dew-point temperature of the room to be controlled. That is, in the present invention, the lower limit value for the temperature for the supply air may be calculated based on the dew-point temperature of the exhaust air from the room to be controlled, or the lower limit value for the temperature of the supply air may be calculated based on the dew-point temperature of the supply air from the outside conditioning equipment. Additionally, in the present invention, the outside conditioning equipment need not necessarily be provided, where, in the case wherein the outside conditioning equipment is not provided, one may consider calculating the lower limit value for the temperature of the supply air based on the dew-point temperature of the outside air. Additionally, the present invention may be structured as an air-conditioning controlling device to which an air-conditioning controlling method as set forth above is applied.

Given the present invention, the dew-point temperature of the room that is subject to control (or the dew-point temperature of the exhaust air, or the dew-point temperature of the supply air from an outside air-conditioning device, or the dew-point temperature of the outside air) is measured, a lower limit value for the temperature of the supply air wherein there would be no danger of the occurrence of condensation within the room that is subject to control is calculated based on the measured dew-point temperature, and a setting value for the temperature of the supply air and a setting value for the flow rate of the supply air are determined based on the calculated lower limit value for the temperature of the supply air, and thus the temperature of the supply air can be decreased, and the flow rate of the supply air can be reduced commensurately, enabling the achievement of energy conservation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating schematically an example of an air-conditioning controlling system to which is applied the air-conditioning controlling method according to the present invention.

FIG. 2 is a functional block diagram illustrating the critical components of an air-conditioning controlling device in the air-conditioning controlling system according to the example.

FIG. 3 is a diagram illustrating schematically another example of an air-conditioning controlling system to which is applied the air-conditioning controlling method according to the present invention.

FIG. 4 is a functional block diagram illustrating the critical components of an air-conditioning controlling device in the air-conditioning controlling system according to the other example.

FIG. 5 is a diagram illustrating an example of setting characteristics I for the temperature of the supply air and setting characteristics II for the flow rate of the supply air used in the air-conditioning controlling system according to the other example.

FIG. 6 is a diagram illustrating a comparison of the different setting characteristics I for the temperature of the supply air and setting characteristics II for the flow rate of the supply air when the lower limit value for the temperature for the supply air is high and when the lower limit value for the temperature of the supply air is low.

FIG. 7 is a diagram illustrating an example wherein a dew-point temperature sensor is provided in an exhaust duct for the air exhausted from within a data center.

FIG. 8 is a diagram illustrating an example wherein a dew-point temperature sensor is provided in a supply duct for the supply air from an outside conditioning equipment to a data center,

FIG. 9 is a diagram illustrating an example wherein a dew-point temperature sensor is provided in a supply duct for outside air into a data center when no outside conditioning equipment is provided.

FIG. 10 is a diagram illustrating schematically a conventional air-conditioning controlling system.

DETAILED DESCRIPTION OF THE INVENTION

Examples of the present invention are explained in detail below based on the drawings.

FIG. 1 is a diagram illustrating schematically an example of an air-conditioning controlling system to which is applied an air-conditioning controlling method. In this figure, codes that are the same as those in FIG. 10 indicate identical or equivalent structural elements as the structural elements explained in reference to FIG. 110, and explanations thereof are omitted.

The point that is different from the conventional system illustrated in FIG. 10 is in the functions possessed by the air-conditioning controlling device 4. In this first form of embodiment, the air-conditioning controlling device 4 is defined as 4A, to differentiate from the air-conditioning controlling device in the conventional system.

Additionally, a dew-point temperature sensor 9 for measuring the dew-point temperature within the data center 1 is provided within the data center 1, to send a measured value trpv for the dew-point temperature from the dew-point temperature sensor 9 to the air-conditioning controlling device 4.

Additionally, in this example, an inverter INV is provided in a fan 2-2 of an air-conditioning device 2 to provide speed variation, and the flow rate of the fan 2-2 (the supply air flow rate) is controlled through controlling the percentage value of the inverter output (fan INV) to the inverter INV from the air-conditioning controlling device 4A.

The air-conditioning controlling device 4A is achieved through hardware, having a processor and a storage device, and a program that works in conjunction with this hardware to produce various functions, and has a function for determining a setting value for a supply air temperature and for a supply air flow rate into the data center 1 from the air-conditioning device 2 as a function that is unique to the present example.

FIG. 2 illustrates a functional block diagram of the critical components of the air-conditioning controlling device 4A. The functions for determining the setting values for the supply air temperature and for the supply air flow rate, possessed by the air-conditioning controlling device 4A will be explained below while switching the functions of the individual portions of the functional block diagrams.

The air-conditioning controlling device 4A is provided with a supply air temperature lower limit value calculating portion 401, an equipment-constrained supply air temperature lower limit value storing portion 402, a supply air temperature setting value determining portion 403, a supply air flow rate setting value determining portion 404, a COMP INV outputting portion 405, and a fan INV outputting portion 406.

Note that in the present example, the COMP INV outputting portion 405 and the fan INV outputting portion 406 are provided in the air-conditioning controlling device 4A; however, in an actual system, usually a dedicated controller (not shown) would be provided for the air-conditioning device 2, and when this type of dedicated controller is provided for the air-conditioning device 2, the dedicated controller is structured having the COMP INV outputting portion 405 and the fan outputting portion 406. In this case, the COMP INV outputting portion 405 and the fan INV outputting portion 406 are eliminated from the air-conditioning controlling device 4A, and the setting values determined by the supply air temperature setting value determining portion 403 and the supply air flow rate setting value determining portion 404 are sent to the dedicated controller.

The supply air temperature lower limit value calculating portion 401 inputs the measured value trpv of the dew-point temperature within the data center 1 the indoor dew-point temperature) from the dew-point temperature sensor 9, and adds, to the measured value trpv of the dew-point temperature a margin portion a that is determined in advance, to calculate a lower limit value tsmin1 for a supply air temperature wherein there is no danger of the occurrence of condensation within the data center 1 (tsmin1=trpv+α). That is, a lower limit value tsmin1 for the supply air temperature, wherein there is no danger of dehumidification (including dehumidification by the coil 2-1) occurring within the data center 1 by the air from the air-conditioning device 2 is calculated. Note, the margin portion α may be varied by evaluating, from the CO₂ concentration within the room, the approximate number of people (to estimate the amount of moisture that will be produced within the room). Furthermore, the approximate number of people can also be understood from, for example, information from a security system, or the like, rather than just from the CO₂ concentration.

The supply air temperature setting value determining portion 403 inputs the lower limit value tsmin1 for the supply air temperature, calculated by the supply air temperature lower limit value calculating portion 401, and compares this supply air temperature lower limit value tsmin1 to the equipment-constrained supply air temperature lower limit value tsmin2 that is stored in the equipment-constrained supply air temperature lower limit value storing portion 402, and defines the higher of the supply air temperature lower limit values as the supply air temperature setting value tssp. Here the equipment-constrained supply air temperature lower limit value tsmin2 is a supply air temperature lower limit value that is controlled by the capability of the air-conditioning device 2, and indicates the lower limit value of the supply air temperature range described in, for example, a catalog.

The supply air flow rate setting value determining portion 404 inputs the setting value tssp for the supply air temperature, determined by the supply air temperature setting value determining portion 403, and determines the setting value Qssp for the supply air flow rate as Qssp (CMH)=rated capability (kW)×3600/{(assumed inlet temperature−tssp)×specific mass (kg/m³)}. Note that in the calculation formula for this setting value Qssp, the “assumed inlet temperature” is the temperature of the intake that is anticipated with the air-conditioning device 2 operating at rated capability, and indicates the rated inlet temperature found in the catalog, or the like. Moreover, the “rated capability” is the rated cooling capability of the air-conditioning device 2.

The COMP INV outputting portion 405 inputs the measured value tspv for the supply air temperature into the data center 1 from the supply air temperature sensor 7 and the setting value tssp for the supply air temperature, determined by the supply air temperature setting value determining portion 403, and adjusts the inverter power (COMP INV) to the compressor 8 so that the measured value tspv for the supply air temperature will match the setting value tssp for the supply air temperature.

The fan INV outputting portion 406 inputs the setting value Qssp for the supply air flow rate, determined by the supply air flow rate setting value determining portion 404, and adjusts the inverter output to the inverter INV (the fan INV) so that the supply air flow rate Qs from the fan 2-2 will be Qssp.

In this way, the setting value tssp for the supply air temperature is set to as low a value as possible such that there is no danger of the occurrence of condensation within the data center 1, depending on the dew-point temperature trpv within the data center, measured by the dew-point temperature sensor 9, and a setting value Qssp for the supply air flow rate is determined so as to be suitable for the setting value tssp for the supply air temperature, reducing the supply air temperature, and reducing the supply air flow rate commensurately, enabling energy conservation.

Note that when calculating the setting value Qssp for the supply air flow rate in the present form of embodiment, a small value that takes safety into consideration can be added to the setting value Qssp for the supply air flow rate. While there is the danger of the interior of the data center 1 becoming too hot, depending on the load of the electronic equipment that is contained within the rack 3, adding, to the setting value Qssp for the supply air flow rate, the small value that takes safety into account makes is possible to ameliorate the problem of the interior of the data center 1 becoming too hot.

FIG. 3 is a diagram illustrating schematically another example of an air-conditioning controlling system to which the air-conditioning controlling method according to the present invention is applied. Here, a temperature sensor 10 for measuring, as the present temperature, the temperature within an inlet side of a rack 3 is provided in the data center in addition to the dew-point temperature sensor 9 for measuring the dew-point temperature within the data center 1, where the measured value trpv for the dew-point temperature, from the dew-point temperature sensor 9, and the measured value tpv of the present temperature, from the temperature sensor 10, are sent to the air-conditioning controlling device 4 (4B).

Additionally, as with the first form of embodiment, in the second form of embodiment an inverter INV is provided in a fan 2-2 of an air-conditioning device 2 to provide speed variation, and the flow rate of the fan 2-2 (the supply air flow rate) is controlled through controlling the percentage value of the inverter output (fan INV) to the inverter INV from the air-conditioning controlling device 4B.

FIG. 4 illustrates a functional block diagram of the components of the air-conditioning controlling device 413. The functions for determining the setting values for the supply air temperature and for the supply air flow rate, possessed by the air-conditioning controlling device 4B are explained below while switching the functions of the individual portions of the functional block diagrams.

The air-conditioning controlling device 4B has: a supply air temperature lower limit value calculating portion 411, an equipment-constrained supply air temperature lower limit value storing portion 412, a supply air temperature lower limit value determining portion 413, a requested temperature storing portion 414, a supply air temperature setting value determining portion 415, a supply air flow rate setting value determining portion 416, a COMP INV outputting portion 417, and a fan INV outputting portion 418. Note that the requested temperature storing portion 414 stores, as a requested temperature tsp, a requested value relative to the present temperature tpv measured by the temperature sensor 10.

As with the supply air temperature lower limit value calculating portion 401 in the first form of embodiment, the supply air temperature lower limit value calculating portion 411 inputs the measured value trpv of the dew-point temperature within the data center 1 (the indoor dew-point temperature) from the dew-point temperature sensor 9, and adds, to the measured value trpv of the dew-point temperature a margin portion a that is determined in advance, to calculate a lower limit value t s min1 for a supply air temperature wherein there is no danger of the occurrence of condensation within the data center 1 (tsmin1=trpv+α)

The supply air temperature lower limit value determining portion 413 inputs the lower limit value tsmin1 for the supply air temperature, calculated by the supply air temperature lower limit value calculating portion 411, and compares this supply air temperature lower limit value tsmin1 to the equipment-constrained supply air temperature lower limit value tsmin2 that is stored in the equipment-constrained supply air temperature lower limit value storing portion 412, and defines the higher of the supply air temperature lower limit values as the supply air temperature setting value tsmin.

The supply air temperature setting value determining portion 415 inputs the supply air temperature lower limit value tsmin determined by the supply air temperature lower limit value determining portion 413, the present temperature tpv from the temperature sensor 10, and the requested temperature tsp, stored in the requested temperature storing portion 414, to determine the setting value tssp for the supply air temperature in accordance with the setting characteristics I for the supply air temperature shown in FIG. 5.

That is, the supply air temperature lower limit value tsmin is used as a control parameter to hold the setting value tssp for the constant supply air temperature as the supply air temperature lower limit value tsmin in a range wherein the present temperature tpv is higher than tx, but when the present temperature tpv is in the range that is lower than tx, the setting value tssp for the supply air temperature increases with the magnitude of the deviation from the requested temperature tsp.

The load within the data center can be reduced through having this type of supply air temperature setting characteristics I, where, when the present temperature tpv is less than tx, the setting value tsp for the supply air temperature is increased, enabling a reduction in the capability of the air-conditioning device 2. Doing so prevents excessive cooling in the data center 1, thus conserving energy.

The supply air flow rate setting value determining portion 416 inputs the supply air temperature lower limit value tsmin determined by the supply air temperature lower limit value determining portion 413, the present temperature tpv from the temperature sensor 10, and the requested temperature tsp, stored in the requested temperature storing portion 414, to determine the setting value Qssp for the supply air flow rate in accordance with the setting characteristics II for the supply air flow rate shown in FIG. 5. That is, the supply air temperature lower limit value tsmin is used as a control parameter, and prior to having the supply air temperature setting value tssp be a constant at tsmin, the setting value Qssp for the supply air flow rate is held at a constant at a lower limit value that has been set in advance, but after the setting value tssp for the supply air temperature has been caused to be constant at tsmin, then the supply air flow rate setting value Qssp will increase in accordance with the magnitude of deviation from the requested value tsp.

The use of the sating characteristics II for the supply air flow rate in this way enables energy conservation by causing the setting value Qssp for the supply air flow rate to be a constant at the lower limit value when the load within the data center 1 is small, but when the load within the data center 1 increases so that the present temperature tpv rises above tx, then the setting value Qssp for the supply air flow rate increases, to prevent the interior of the data center 1 from becoming hot.

The COMP INV outputting portion 417 inputs the measured value tspv for the supply air temperature into the data center 1 from the supply air temperature sensor 7 and the setting value tssp for the supply air temperature, determined by the supply air temperature setting value determining portion 415, and adjusts the inverter power (COMP INV) to the compressor 8 so that the measured value tspv for the supply air temperature will match the setting value tssp for the supply air temperature.

The fan INV outputting portion 406 inputs the setting value Qssp for the supply air flow rate, determined by the supply air flow rate setting value determining portion 416, and adjusts the inverter output to the inverter INV (the fan INV) so that the supply air flow rate Qs from the fan 2-2 will be Qssp.

FIG. 6 illustrates the supply air temperature setting characteristics I and the supply air flow rate setting characteristics II that vary using the supply air temperature lower limit value t s min has a control parameter. The characteristics I H and II H indicate the supply air temperature setting characteristics and the supply air flow rate setting characteristics when the lower limit value tsmin for the supply air temperature is high, and the characteristics I L and II L indicate the supply air temperature setting characteristics and the supply air flow rate setting characteristics when the lower limit value tsmin for the supply air temperature is low. It can be seen, from the changes in these setting characteristics as well, that reducing the supply air temperature lower limit value tsmin can reduce the supply air flow rate (the fan INV output) even when about the same amount of cooling is requested.

Note that while a dew-point temperature sensor 9 was provided within the data center 1 in the example set forth above, to measure the dew-point temperature within the room, the dew-point temperature of the exhaust gas by the exhaust fan 6 from the data center 1 may be measured, or the dew-point temperature of the supply air from the outside conditioning equipment 5 into the data center 1 may be measured instead.

That is, in the case of an example, as illustrated in FIG. 7, a dew-point temperature sensor 9 may be provided in an exhaust duct for exhaust air by an exhaust fan 6 from within the data center 1, and a lower limit value tsmin1 for the supply air temperature may be calculated from the measured value trpv for the dew-point temperature from the dew-point temperature sensor 9, or, as illustrated in FIG. 8, a dew-point temperature sensor 9 may be provided in a supply duct for supply air from the outside conditioning equipment 5 into the data center 1, and a lower limit value tsmin1 for the supply air temperature may be calculated from the measured value trpv for the dew-point temperature from the dew-point temperature sensor 9.

Moreover, while an outside conditioning equipment 5 was provided in the forms of embodiment set forth above, the outside conditioning equipment 5 need not necessarily be provided. If no outside conditioning equipment 5 is provided, then, as illustrated in FIG. 9, in the first form of embodiment, for example, one may consider providing the dew-point temperature sensor 9 in a supply air duct for the outside air into the data center 1, to calculate the lower limit value tsmin1 for the supply air temperature from the measured value trpv for the dew-point temperature from the dew-point temperature sensor 9.

Furthermore, while in the examples set forth above a dew-point temperature sensor 9 was provided to measure the dew-point temperature, instead both the temperature and the humidity may be measured, and the dew-point temperature can be calculated from the measured temperature and humidity. In the present invention, the concept of measuring the dew-point temperature includes calculating the dew-point temperature from a measured temperature and humidity.

Furthermore, while in the examples set forth above the cooling medium circulating rate adjusting device 8 was a compressor (COMP), of course one may consider a variety of mechanisms that can be operated, such as an expansion valve or a hot gas bypass valve, or the like, as the cooling medium circulating rate adjusting device 8.

The air-conditioning controlling method and device according to the present invention, as an air-conditioning controlling method and device that controls the supply air temperature and the supply air flow rate from an air-conditioning device to a room that is subject to control, wherein is placed equipment wherein there is the danger of physical damage through condensation, can be applied to, for example, a data center wherein is placed electronic equipment, such as servers, as the room that is subject to control. 

1. An air-conditioning controlling method for controlling a supply air temperature and a supply air flow rate from an air-conditioning device to a room that is subject to control, wherein a room wherein is placed equipment wherein there is the danger of occurrence of physical damage through condensation is placed is the room that is subject to control, comprising the steps of: measuring a dew-point temperature of the room that is subject to control; calculating a lower limit value for a supply air temperature wherein there is no danger of the occurrence of condensation in the room that is subject to control; determining a setting value for the supply air temperature based on the calculated lower limit value for the supply air temperature; and determining a setting value for the supply air flow based on the calculated lower limit value for the supply air temperature.
 2. The air-conditioning controlling method as set forth in claim 1, wherein: the step for determining the setting value for the supply air temperature uses a lower limit value for the supply air temperature that is constrained by a. capability of the air-conditioning device as an equipment-constrained supply air temperature lower limit value, and compares the equipment-constrained supply air temperature lower limit value to the calculated supply air temperature lower limit value and selects the higher supply air lower limit value as the setting value for the supply air temperature.
 3. The air-conditioning controlling method as set forth in claim 1, wherein: instead of the step for measuring the dew-point temperature of the room that is subject to control, a step is provided for measuring a dew-point temperature of exhaust air from the room that is subject to control, a dew-point temperature of supply air, from an outside conditioning equipment that processes outside air and supplies it to the room that is subject to control, or a dew-point temperature of the outside air.
 4. An air-conditioning controlling device for controlling a supply air temperature and a supply air flow rate from an air-conditioning device to a room that is subject to control, wherein a room wherein is placed equipment wherein there is the danger of occurrence of physical damage through condensation is placed is the room that is subject to control, comprising: a dew-point temperature measurer measuring a dew-point temperature of the room that is subject to control; a supply air temperature lower limit value calculator calculating a lower limit value for a supply air temperature wherein there is no danger of the occurrence of condensation in the room that is subject to control; a supply air temperature setting value determiner determining a setting value for the supply air temperature based on the calculated lower limit value for the supply air temperature; and a supply air flow rate setting value determiner determining a setting value for the supply air flow based on the calculated lower limit value for the supply air temperature.
 5. The air-conditioning controlling device as set forth in claim 4, wherein: the supply air temperature setting value determiner means use a lower limit value for the supply air temperature that is constrained by a capability of the air-conditioning device as an equipment-constrained supply air temperature lower limit value, and compare the equipment-constrained supply air temperature lower limit value to the calculated supply air temperature lower limit value and select the higher supply air lower limit value as the setting value for the supply air temperature.
 6. The air-conditioning controlling device as set forth in claim 4, wherein: instead of the dew-point temperature measurer measuring the dew-point temperature of the room that is subject to control, the dew-point temperature measurer measuring a dew-point temperature of exhaust air from the room that is subject to control, a dew-point temperature of supply air, from an outside conditioning equipment that processes outside air and supplies it to the room that is subject to control, or a dew-point temperature of the outside air. 